Welcome to Yorkie Talk and congratulations on your new pup! If she is 8 weeks old, be prepared to be patient with potty training.
Limited her roaming freedom to a smallish area with the piddle pad. One room when you can supervise, and an xpen or small room when you cannot supervise.
When she uses the pad, praise her profusely! Give her a little treat reward. Keep potty training a positive experience. If she has an accident, don't scold her. Just say, "Uh oh!" and remind her about the pad. Clean up the accident spots with an enzyme cleaner.
Keep the pad changed fairly frequently. Sometimes pups are reluctant to return to a pad that is used too many times. My older boy was funny and would not poop on a pad that he had peed on.
Here is my blog about potty training:
Potty Training Small Dogs - Dog Life and Style